Sulfur slurry preparation in pipelines

ABSTRACT

AN IMPROVED SULFUR-OIL SLURRY RESISTANT TO AGGLOMERATION BY ADDITION THERETO OF A SMALL AMOUNT OF AN ASPHALTIC MATERIAL.

Rouald K.

SULFUR SLURRY PREPARATION liN PIPELINES June, Pleasant Hill, Calif, assiguor to Shell *Qil Eompany, New York, N.Y. No Drawing. Griginal application Dec. 18, 1968, Ser. No.

784,925, now Patent No. 3,582,147. Divided and this application May 10, 1971, Ser. No. 142,009

Int. Cl. B011 13/00 US. Cl. 252-309 6 Claims ABSTRACT OF THE DISCLOSURE An improved sulfur-oil slurry resistant to agglomeration by addition thereto of a small amount of an asphaltic material.

The invention relates to an improved and novel process of preventing sulfur agglomeration, sticking, deposition and plugging of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry.

CROSS-REFERENCE This application is a division of co-pending application Ser. No. 784,925, now US. Pat. No. 3,582,147.

BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to US. Pats. 2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry, June 1967, pp. 58-60. In making the sulfur into a sulfurhydrocarbon slurry, the sulfur is generally sprayed in molten form into either water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, agglomeration and separation of the sulfur from the carrier fluid, plating, depositing or coating of the sulfur on pipeline walls causing plugging of the pipeline, corrosion, particle attrition and viscosity changes due to pressure and temperature variations requiring greater pumping power which increases operation costs, etc., are only a few of the problems normally encountered in transporting sulfur-liquid hydrocarbon slurries through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, neverthless the transportation of sulfur in slurry form through pipelines can be made to be an effective, attractive and economic means of sulfur transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transportation of sulfur slurries such as injecting molten sulfur into Water or a liquid hydrocarbon thereby forming a sulfur slurry for pipeline transportation. These methods 3,745,122 Patented July 10, 1973 for making sulfur slurries suitable for transporting through pipelines generally do not overcome the ag glomeration, attrition, deposition, sticking, coating and/ or plugging problems described above.

An object of the present invention is to transportsulfur as a sulfur-liquid hydrocarbon slurry through pipelines which is stable and fiowable.

Still another object of the present invention is to transport through a pipeline sulfur-liquid hydrocarbon slurries without causing sulfur agglomeration, coating, deposition or plug ing of the pipeline.

Still another object of this invention is to form a slurry of sulfur in a liquid hydrocarbon medium, which when formed is stable, does not tend to cause sticking, agglomeration or plugging of equipment during the making of the slurry or on storage or pipeline plugging or cause any difficulty in circulation of the slurry when said slurry is pumped and transported through a pipeline and from which the sulfur can be readily recovered at the terminal end of the pipeline as essentially pure sulfur.

Another object is to transport sulfur as a liquid hydrocarbon slurry by pipeline over great distances under conditions of reduced pumping and handling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to an improved, novel and new technique for making a sulfur-liquid petroleum slurry and transporting a slurry of a sulfur-liquid petroleum through pipelines over great distances without causing sulfur agglomeration or sticking during the slurry preparation or on its subsequent storage, if necessary, or when pipeline transporting the slurry so that sulfur deposition on the walls of the pipelines due to the tendency of sulfur under such conditions to adhere to the pipeline walls because of temperature, pressure and other variable conditions so as to plug said lines; by admixing or adding or injecting prior to or after injection into the pipeline of a slurry of sulfur and a liquid petroleum, a small amount of from 0.01 to 10%, preferably between about 0.5% to about 5%, of an asphaltenic material derived or obtained or present in crude oil and preferably an unrefined crude oil. The asphaltenic material can be added to the slurry of sulfur and liquid petroleum prior to or during the making of the slurry or the asphaltenic material can be injected when necessary in various places along the pipeline where indications are that the slurry might cause sulfur agglomeration, deposition, sticking or plugging of the line. Any plugging detection means known in the art can be used for this purpose. It has been noted that by adding or injecting into a slurry of the sulfur and liquid petroleum in which the sulfur content of the slurry can vary from about 10% by weight to about 75% by weight or higher, preferably between 30% by weight and by weight, sulfur, e.g., kerosene or oil distillates or condensates or crude oil during or after the slurry preparation from about 0.01 to 10% of an asphaltenic material, that not only does its presence prevent plugging of pipelines transporting said slurry but also preventing agglomeration, sticking and deposition of sulfur on the walls of the pipe- 3 lines and improves flow of the slurry and reduces pump ing costs.

The sulfur-liquid petroleum slurry can be made by any suitable means such as described in US. Pat. 2,798,772 or by the method described in US. Pat. 3,443,837, fiied Aug. 28, 1967. It is preferred that in the making the sulfur-liquid petroleum fraction slurry that the sulfur is produced in spherical form since sulfur in this form in the slurry is more stable and is resistant to agglomeration, separation, attrition and friction.

The phase transfer method for making sulfur slurry as described in the above-mentioned copending application comprises first forming a sulfur-aqueous liquid (water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon. Thereafter, the crude oil can be added as desired.

The liquid petroleum carrier for the sulfur can be one ranging in viscosity from a light petroleum fraction such as liquefied petroleum gas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleum distillates, condensates, crude oil and mixtures thereof. Preferred are liquid petroleum containing at least or higher of aromatics, preferably about 1530% aromatic enriched kerosene or oil condensate fractions or crude oil containing -80% aromatics which include monoand polyaromatic hydrocarbons.

The asphaltenic additive can be obtained from unrefined or refined crude oil and fractions thereof. By unrefined crude oil is meant any crude oil which has not been processed in a refinery. Thus, a crude oil mfi'be used as it is removed from the ground; or it may be first processed in field units such as oil-water separators, degasers, etc. Although just how the asphaltenes function in the slurry mixture is not understood, it has been found that the asphaltenes prevent sulfur agglomeration, sticking and aid in the formation of spherical sulfur particles having dimensions of from 1 to 800 microns and preferably between and 400 microns.

The asphaltenes can be recovered from petroleum stocks by any suitable means such as described in the Journal of the Institute of Petroleum, February 1968, pages 50-53 and April 1968, pages 107-114 or as described in US. Pats. 3,206,388; 3,228,870; 3,153,623; 2,729,589; 3,368,876; 3,364,138; 3,206,388 and 3,275,076. The latter two patents base materials can be used per se as the asphaltene additive and carrier for the slurry. In other words high asphaltenic crudes or fractions thereof containing at least 1% asphaltenes can be used both as the carrier and additive for the sulfur slurry. The asphaltenes, asphalto genic acids and carboids and their method of recovery and separation from crudes and fractions thereof is also fully described in Chapter 9 of the Sachanens book on The Chemical Constituents of Petroleum and includes petroleum resins, asphaltenes, asphaltogenic acids and their derivatives. Also, the asphaltenic materials described in US. Pats. 3,275,076; 3,284,340 or 3,336,146 can be used and they can be separated from petroleum by methods described in US. Pats. 3,364,138 and 3,368,876.

During the preparation of the slurry as the molten sulfur is dispersed into liquid petroleum containing active asphaltenic components to aid in the making of spherical sulfur particles as well as prevent agglomeration, sticking and the like, the slurry can be cooled effectively by vapor cooling such as described in US. Pat. 2,632,691 or by use of volatile organic materials such as low molecular weight hydrocarbons or chlorinated hydrocarbons in which case the process should be carried out under pressures as described in US. Pat. 2,316,673.

At the terminal end of the line the sulfur can be readily separated from the slurry by any suitable means.

4 PREFERRED EMBODIMENT OF THE INVENTION (I) A 40-60% sulfur-aromatic (17%) enriched kerosene slurry was prepared by phase transfer by first injecting molten sulfur into an aqueous liquid such as water and thereafter contacting the slurry thus formed with the aromatic enriched kerosene to effect phase transfer of the sulfur particles into the aromatic enriched kerosene. To the sulfur-kerosene slurry was added from about 1% to about 2% of asphaltenes and thereafter this slurry was injected into a pipeline for transportation to a terminal station. Sulfur-kerosene slurries containing a small amount of crude oil thus formed do not form agglomerates or did they plug the pipeline. Instead of using the phase transfer technique for making the slurry, molten sulfur can be injected into the kerosene directly and thereafter admixed with a small amount (12%) asphaltenes.

(II) An advantage of the present process for transporting through pipelines sulfur-liquid petroleum slurries as defined is that the slurry can be also prepared by direct injection of molten sulfur into a suitable petroleum fraction such as kerosene, fuel oil, oil condensate or distillate crude oil and mixtures thereof to which has been added a small amount of asphaltenes so as to aid in making spherical sulfur particles and prevent sulfur agglomeration deposition and plugging of pipelines. Either process as Well as other processes can be used to make the sulfurliquid petroleum fraction slurry depending on the availability of the carrier. Thus, where water is available the first process can be used and if not the second one can be used.

The presence of a small amount of an asphaltenic material during the preparation of the slurry by method (I) or (II) has an additional advantage in that an asphaltenic material aids in the formation of spherical sulfur particles which are most desirable since spherical sulfur particles in slurries as defined provide optimum pipeline performance such as low pressure drops during its transportation and ease of recovery and purification at the terminal end of the pipeline.

The following examples illustrate the essence of the present invention.

(A) Molten sulfur at -180 C. was sprayed into aromatic (17%) enriched kerosene through a spray nozzle at about 200 p.s.i. pressure drop to give a homogeneous slurry with sulfur solids content of about 16% volume in which the sulfur particles were essentially large angularcrystalline particles which began to stick together and agglomerate into a sticky mass within about 10-15 minutes.

(B) The method of (A) was repeated except that 1% 0f asphaltenes was added to the kerosene carrier. The particles formed were microspherical (20-450 microns) in shape and no tendency of the particles to stick or agglomerate were observed for over 24 hours.

In another test different petroleum fractions were used to form sulfur slurries wherein a 90-ml. portion of molten sulfur at C. was injected as a continuous stream for 0.5 minute into a well-stirred 500 ml. charge of a pctroleum carrier. As shown in Table 1 some of the carriers were used neat and to some were added crude oils or crude oil residue products. For comparison various surfactants were also tested as additives to the carriers as shown in Table 1.

From Table 1 is can be seen that only the carriers containing the asphaltenes added as such, or that are indigenous to heavy crude oils, performed satisfactorily. That is, with asphaltenes predispersed in the carriers, high degrees of sulfur particle sphericity were attained and at the same time agglomeration losses of sulfur particles to coagulum were suppressed.

TABLE 1.-EFFECT OF ADDITIVES ON SULFUR DISPERSION INTO PETROLEUM FRACTIONS lConditions: 500 ml. carrier in 1-1iter Morton flask. 90 ml. sulfur at approitrimateltydll w 0. added in 0.5 minute. 1,200 rpm. with crescent blade stirrer excep as no e Coagulnm (+12 mesh) Weight, Particle Initial Level, percent median sphericity, temp, percent weight particle percent Experiment Carrier weight Type basis S ied size, do, p weight a 1 Petroleum fraction (Waterton 22 None 19.1 680 4 condensate). 2 do. 22 1 Bryton 430 (62% alkylaryl sulfonate) 20. 4 710 3 do. 24 1 Oleic acid 30 770 1 4 do. 21 1 50%ddodecyltrimethylarnmonium chlo- 13.8 700 n e. 5 do. 22 1 Dodecylamine 8, 7 630 21 6 t 22 1 Asphaltenes. Nil 600 67 7 do. 3 0. --dO 4.9 700 54 8 do b 23 0.1 6 kPlffrude oil (26% weight asphal- 7.0 690 39 cues 9 1 ,1, 2 1 Crude oil deasphalted residue resins 6.3 680 55 10 do. 2a 1 Crude oil dcasphalted residue aromatics. 20. 3 680 11 Hexane 22 0.1 Asphaltenes 8.0 730 43 12 Fresh Medicine River crude d 60 None 1,4 315 1 o 13 Deasplhaltled Medicine River 60 None (3 9% asphaltenes removed) 5.7 400 12 Glll e 01 14 i. White oil (viscosity 0., 60 5 29 API crude oil (17% weight asphal- 1 13 35 172 cs.). tenes).

a Portion of 30, +50 mesh sulfur particle fraction which rolls down an inclined phase (Sl0pe=1" in b Derived from Canadian oil field. API gravity=5 i.9; viscosity, cs. 59 F.=0.95 and 77 F =0,3 fla h point tag open cup, 0 F =7; point, F. 80; FIA, percent volume satnrates=82 and aromat1es=18.

* API gravity=35.6; viscosity, cs. 59 F.=9.1 and 77 F.=6.9; B.S. and W. percent volume=0,6; flash point, tag open cup, 0 Fa; pour point,

d 600 rpm. agitator speed used in all 60 0. runs. u fur Slurfies of Presellt invention containing Small fraction selected from the group consisting of petroleum amounts of asphaltcnic additives can be transported distillate and petroleum condensate fractions and includthrough pipelines over great distances Without the danger i (11% to about 10% of an h l of sulfur deposition, aggl Sticking P g 2. The slurry composition of claim 1 wherein the liquid of the pipelines. petroleum is a petroleum condensate containing from At the terminal end of the line the sulfur can be re- 10% to 30% aromatics,

moved from the liquid hydrocarbon by suitable mea s 3. The slurry composition of claim 1 wherein the liquid such as descr b in 2,798,772 and the Sulfur petroleum is a petroleum distillate containing from 10% purified by methods as described in U.S. Pat. 2,809,885 to 30% aromatics or U.S. Pat. 3, Which comprises treating Oil @011- 4- A stable non-agglomerating sulfur-petroleum contaminated sulfur with an aqueous solution containing d t slurry comprising from 30% to 70% lf i a mixture of alkali hydrosulfide and corresponding hypetroleum condensate containing from 10% to 30% arod -a, ammonium hydrosulfide and ammonium matics and including from about 0.5% to 5% of asdroxide or by other suitable means such as sulfur can be phaltene.

recovered from the oil slurry by centrifugation or filtra- A stable nomagglomerating s lfup etrole i tion of particulate sulfur, melting the particles and liquidlate Slurry comprising from 30% to 70% l u in pe liquld extractlon.wlth hydrocarbon q coil/[wrung 5 troleum distillate containing from 10% to 30% aromatics 10-5O% aromatics. Thus, at the receiving terminal the and including from about 0.5% to of asphaltene. sulfur slurry can be filtered and washed. The recovered 6 A Stable nomagglomerafing Sulfur oil Slurry comsulfur is then melted and purified by liquid-liquid extracprising from about 307 to about 700/ Sulf r in h romatic h drocarbon such as cumcnt. Also, 0 0 11 1 Connon Wlt an a y taming from about 0.1% to about 10% of asphaltenes if desired, the sulfur can be steam stripped to remove any dlifiiglved solvent and then filtered to recover bright yellow References Cited s The foregoing description of the invention is merely UNITED STATES PATENTS intended to be explanatory thereof. Various changes in 2,643,202 6/1953 Burton et al. 252--309 UX the details of the described method may be made within 3,380,784 4/1963 Yingst et the scope of the appended claims without departing from the spirit of the invention. JOHN D. WELSH, Primary Examiner I claim as my invention. 1. A stable non-agglomerating sulfur-liquid petroleum U.S. Cl. X.R.

slurry comprising 10-70% sulfur in a liquid petroleum 52-384 

